Microstructure Development of 308L Stainless Steel During Additive Manufacturing

Brown, Donald W.; Losko, Adrian S.; Carpenter, John S.; Cooley, J. C.; Clausen, B.; Dahal, Jinesh; Kenesei, Péter; Park, Jun-Sang

doi:10.1007/s11661-019-05169-1

Cited by 20 publications

(13 citation statements)

References 30 publications

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“…There has been considerable work recently to examine microstructural evolution in situ during simulated AM [22][23][24] or similar high solidification rate processes. [13,25,26] However, the high cooling rates associated with AM, estimated at 10 3 K/s [27] to 10 6 K/s [28] depending on the process type, demand measurement rates of kHz to MHz. This, in turn, forces sacrifices in data quality that limits the amount of quantitative microstructural information (e.g., phase fraction, texture, internal stress) that can be gleaned from the diffraction data.…”

Section: Introductionmentioning

confidence: 99%

“…This, in turn, forces sacrifices in data quality that limits the amount of quantitative microstructural information (e.g., phase fraction, texture, internal stress) that can be gleaned from the diffraction data. [22,24,27,29] In contrast, relatively few in situ studies of the evolution of the metastable AM microstructure during post-build heat treatments are to be found in the literature [15,[30][31][32] despite the fact that the relatively slow kinetics during heat treatments often enable quantitative determination of relevant microstructural parameters. Hysteretic lattice parameter expansion was observed during in situ heat treatment of shaped metal deposited Ti64 using low energy (8 keV; penetration depth ~0.01 mm) X-rays.…”

Section: Introductionmentioning

confidence: 99%

“…[31] Neutron diffraction measures on Ti64, while penetrating into the bulk of the material, are very slow due to the low coherent neutron scattering cross section of Ti. The advent of high-energy (> 60keV) X-ray beamlines at 3 rd generation synchrotron sources provides an optimal platform to study the microstructural evolution of AM Ti alloys during heat treatment because it enables both bulk penetration and the ability to collect diffraction patterns sufficient for qualitative microstructural analysis at frequencies of order 1 Hz [27] or potentially higher.…”

Section: Introductionmentioning

confidence: 99%

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Evolution of the Microstructure of Laser Powder Bed Fusion Ti-6Al-4V During Post-Build Heat Treatment

Brown

Anghel

Balogh

et al. 2021

Metall Mater Trans A

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The microstructure of additively manufactured Ti-6Al-4V (Ti64) produced by a laser powder bed fusion process was studied during post-build heat treatments between 1043 K (770 °C) and just above the b transus temperature 1241 K (1008 °C) in situ using high-energy X-ray diffraction. Parallel studies on traditionally manufactured wrought and annealed Ti64 were completed as a baseline comparison. The initial and final grain structures were characterized using electron backscatter diffraction. Likewise, the initial texture, dislocation density, and final texture were determined with X-ray diffraction. The evolution of the microstructure, including the phase evolution, internal stress, qualitative dislocation density, and vanadium distribution between the constituent phases were monitored with in situ X-ray diffraction. The as-built powder bed fusion material was single-phase hexagonal close packed (to the measurement resolution) with a fine acicular grain structure and exhibited a high dislocation density and intergranular residual stress. Recovery of the high dislocation density and annealing of the internal stress were observed to initiate concurrently at a relatively low temperature of 770 K (497 °C). Transformation to the b phase initiated at roughly 913 K (640 °C), after recovery had occurred. These results are meant to be used to design post-build heat treatments resulting in specified microstructures and properties.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evolution of the Microstructure of Laser Powder Bed Fusion Ti-6Al-4V During Post-Build Heat Treatment

Brown

Anghel

Balogh

et al. 2021

Metall Mater Trans A

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“…5(a) and (c), there was a distinct core-shell structure at each grain boundary. It may be utilised to determine the orientationdependent lattice parameters with su cient accuracy to assess the phase strain evolution between austenite and ferrite 21 .…”

Section: Characterisation Of An Individual Grainmentioning

confidence: 99%

Mechanical Properties of 316 Stainless Steel Structure produced by Pulsed Micro-plasma Additive Manufacturing

Yuan

Guan

Wang

et al. 2021

Preprint

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An innovative pulsed micro-plasma additive manufacturing (AM) system is proposed for the fabrication of thin-walled 316 stainless steel parts. During the deposition process, the heat accumulation from the micro-plasma can be controlled effectively by adjusting the following parameters: the AM current, pulse length of the plasma arc, and scanning speed. The width of the pool can reach 3.0 mm. The microstructural analysis, micro-hardness tests, and tensile strength tests were performed. The results of the structural characterisation showed that columnar dendrites predominated in the microstructure of thin-walled elements and exhibited epitaxial growth from the bottom to the top and from the middle to both sides, while the top grains had more variations in growth orientation. The grains had a core-shell structure with a growth orientation along the < 100 > direction of the austenite structure, and the boundary was composed of migrated C and Cr. The micro-hardness of the thin-walled structure (240–320 Hv0.3) decreased with increasing the deposition thickness. The tensile strength and yield strength of the thin-walled parts were 669 and 475 MPa, respectively. The fracture mechanism was that cracks formed along the pores along the pores of the grain boundary and then propagated along them, ultimately leading to the fracture.

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“…Fast detectors (up to 20 kHz) have been employed to examine phase evolution under rapid processing [10,[15][16][17][18][19][20][21][22], such as welding and AM processing, and combination with ultrafast imaging provided new insights into the AM process [9,18,22]. Studies with high angular resolution and a relatively large area detector have revealed details of lattice changes for external mechanical and temperature factors [11,[23][24][25][26][27][28]. Our recent report presented an in-situ study of Ni-alloy 718 with a multi-panel area detector with an unprecedented combination of high 2θ-angular resolution and a 250 Hz frame rate [29].…”

Section: Introductionmentioning

confidence: 99%

High speed synchrotron X-ray diffraction experiments resolve microstructure and phase transformation in laser processed Ti-6Al-4V

Lim

Aroh

et al. 2021

Materials Research Letters

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Microstructure Development of 308L Stainless Steel During Additive Manufacturing

Cited by 20 publications

References 30 publications

Evolution of the Microstructure of Laser Powder Bed Fusion Ti-6Al-4V During Post-Build Heat Treatment

Evolution of the Microstructure of Laser Powder Bed Fusion Ti-6Al-4V During Post-Build Heat Treatment

Mechanical Properties of 316 Stainless Steel Structure produced by Pulsed Micro-plasma Additive Manufacturing

High speed synchrotron X-ray diffraction experiments resolve microstructure and phase transformation in laser processed Ti-6Al-4V

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